JPS5918859B2 - Precision position alignment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision position alignment device for precisely aligning two objects such as a mask and a wafer.

A conventional apparatus for aligning two objects in close proximity, such as a mask and a wafer, has a sealed structure shown in FIGS. 1, 2, 3, and 4. That is, in the case of FIG. 1, the mask 1 is fixed to the holding table 1, and the mask holding table T is fixed to the base 9 via the support 8, (-■). On the other hand, the wafer 2 is fixed to a wafer holding table 3, which is supported by a base 9 by a sliding part 4 made of steel balls, rollers, etc.
The position is determined by a motor 6, a feed screw mechanism 5, and a motor 6. For example, when aligning the mask and wafer, the microscope is used more than the mask side.
Observing the corresponding pattern on the mask wafer, motor 6
Alternatively, although not shown, the wafers are moved and aligned by a manual mechanism.

In such conventional technology, the feeding mechanism 5 uses a precision mechanism such as a reduction mechanism using a lever or a Thiesmann mechanism. However, even with these precision mechanisms, sufficient positioning accuracy may not be achieved.

There is a device shown in FIG. 2 that improves this point.
That is, in FIG. 2, the mask 1 is fixed to the base 9 with the same structure as in FIG. Also...holding table 3
The mechanism for positioning the wafer 2 placed thereon includes a coarse movement table 16 that is moved and positioned on a base 9 with a slide portion 4 interposed therebetween by a feed screw mechanism 5 connected to a motor 6; A parallel plate spring 10 with one end planted on the assembly table 16, a fine movement table 15 attached to the other end of the parallel plate spring 10 and having a wafer holding table 3 mounted on its upper surface, and the fine movement table. The opposing iron plate 12 attached to one end of the fine movement table 15, the smooth surface 14 formed on the other end of the fine movement table 15, and the one end of the coarse movement table 16 are attached to the parallel plate spring 10 to cause fine movement. An electromagnet 11 that electromagnetically attracts the opposing iron plate 12 so as to move the table 15 finely, and an electromagnet 11 that is attached to the other end of the coarse movement table 16 and that contacts the smooth surface 14 of the fine movement table 15 to control fine movement of the fine movement table 15. It is composed of a differential displacement meter 13 for detection. Similarly to the wafer holding table 3 shown in FIG. 1, the coarse movement table 16 is moved by the power from the motor 6 and is aligned with a coarse accuracy of 9 degrees.

Further, the fine movement table 15 controls the magnetic absorption force of the electromagnet 11 by feeding back a displacement signal obtained from the differential displacement meter 13, and bends the parallel plate spring 10, thereby achieving accurate position alignment. As explained above (in accordance with the prior art shown in FIGS. 1 and 2), in the positional alignment system of the mask 1 and the wafer 2, there is an indispensable sliding part 4 such as a steel ball or a roller. is intervening.

Normally, the sliding part 4, such as a steel ball or roller, has an oil film, deformation of the contact part, etc., and when positioning in the submicron order is targeted, the lack of rigidity in this part becomes a fatal flaw, making it difficult to perform high-precision positioning. is extremely difficult.

As a conventional technique that corrects this point, the one shown in FIG. 3 is considered. That is, there is no wafer on the coarse movement table 16.
A precision positioning mechanism on which the holding table 3 is mounted, and an electromagnetic support 17 on which the mask holding table 7 on which the mask 1 is fixed are fixed. Further, the upper surface of the mask holding table 7 is in contact with the lower surface of a mask stop electromagnet 18 fixed to the base 9. Hey...
The mask holding table 7 is made of magnetic material and has smooth upper and lower surfaces. So first, mask 1
The mask holding table 7 and the wafer holding table 3 each have a relative position error of several hundred μm.
Place and fix it on. At this time, the mask stop electromagnet 18 is set to 0.
N. Leave the electromagnet of the electromagnet support 17 in the 0FF state. That is, since the mask holding table 7 is fixed to the base 9 by the mask stopping electromagnet 18, only the wafer 2 is moved by the movement of the coarse movement table 16. In this state, move the coarse movement table 16 to separate the mask 1 and wafer.
- Aligns the relative position error of 2 to several microns. next,
The mask stop city electromagnet 18 is set to 0FF, the electromagnet of the electromagnet support 17 is set to 0N, and the mask holding table 7 is set to the coarse movement table 1.
Fixed at 6.

In this state, the precision positioning mechanism moves the wafer 2 and aligns the mask 1 and the wafer 2 so that the relative positional error between them is on the order of submicrons. When precise position alignment is performed in this way, a slide part 4 such as a roller or steel ball is included in the position alignment system of the mask 1 and the wafer 2.
There are no low-rigidity parts, and no errors occur due to insufficient rigidity. However, when moving the coarse movement table to roughly align the position using the mechanism shown in FIG. In addition, during close alignment, the friction between the mask stop electromagnet 18 and the mask holding table 7 causes the result of precise alignment to be
Since the distance between the two is about 0.1 dragon, a distance of about 0.1 dragon must be maintained between the two.

In other words, when the mask holding table is attracted to one electromagnet, when the mask holding table is attracted to one electromagnet, the other In order to maintain non-conflict with the electromagnet,
It is necessary to leave an interval of about 0.1 u. In this way, the distance formed between each electromagnet 17, 18 and the mask holding table 7 becomes too crowded, so after adjusting the rough position, the mask stopping electromagnet 18 is turned off and the electromagnet of the electromagnet support 17 is set to 0N. At this time, the mask holding table 7 is moved downward by an amount corresponding to the above-mentioned interval amount. This causes a left-right positional deviation of several microns, increases the stroke for close positioning, and has the drawback that it is difficult to perform precise positioning with a single operation of slightly moving the fine movement table 15. It was hot.
In other words, since the stroke for precise positioning increases and exceeds the range of fine positioning, it is necessary to move the coarse movement table 15 again to perform coarse position alignment.This operation will be repeated several times, and precise positioning will not be achieved at all. As a result, "-o" is not completed.

} FIG. 4 shows a precision positioning mechanism different from the precision positioning mechanisms shown in FIGS. 2 and 3. That is, a fine movement table 15 supported by an elastic column 20, a drive spring 19 that pushes this from the side, a compression mechanism 21 for the drive spring and a motor 22, and a smooth surface 1 fixed to the fine movement table 15.
4 and a differential transformer 13. This mechanism changes the compressive force of the drive spring 19 by the motor 22, moves the fine movement table by the difference in spring constant between the drive spring and the elastic column, detects the amount of movement by the differential transformer 13, and then changes the compression force of the drive spring 19. By feeding back to the position, the positioning is performed at the tree density vζ in the same way as the precision positioning mechanism shown in FIG. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a close position alignment device with Vc that allows two objects such as a mask and a wafer to be easily aligned with high accuracy.

That is, in the present invention, a first object and a second object are arranged to be aligned, a holding armable is provided on which the first object is placed, and a holding armable is placed on which the second object is placed, and a slight displacement is caused. A given fine movement table is supported by a coarse movement table, and the coarse movement table is slidably supported on a base by a slide member so that coarse displacement can be changed. Attach the first fixing means for fixing to the base,
A second fixing means for fixing the holding table during precise position alignment is attached to the coarse movement table, and when the first fixing means is activated, a repulsive force is applied from the second fixing means to the holding table. When the second fixing means is activated, the first fixing means applies a repulsive force to the holding table, and the holding table and the first fixing means or the second fixing means are held in a non-contact state. It is characterized by the fact that it is made to do so.

The present invention will be specifically explained below based on the embodiment shown in FIG.

That is, this position alignment device includes a coarse movement mechanism consisting of a slide portion 4 such as a steel ball or roller, a feed mechanism 6, a motor 5, and a coarse movement table 16, and a wafer 2 on the coarse movement table 16.
A wafer holding table 3 is placed thereon to fix the wafer, and a differential displacement meter 13, a smooth surface 14, a fine movement table 15, and a drive spring 19 are mounted.
, elastic strut 20, drive spring compression mechanism 21, and motor 2
A precision positioning mechanism consisting of 2, a mask holding table 7 having both ends formed of a magnetic material, and a coarse movement air pipe 26 fixed to both ends of the coarse movement table 16, and a mask holding table 7 having both ends formed of a magnetic material. The electromagnet support 17 is formed to reach the upper surface of each of the opposite ends of the mark holding table 7, and the mark is fixed to the base 9 so as to face both ends of the mark holding table 7, and a fine movement air pipe 27 is connected to the lower surface thereof. It is composed of a mask stopping electromagnet 18 that guides the mask. Therefore, first, the relative position error between the mask 1 and the wafer 2 is set to several hundred μm, and the mask and wafer are fixed to their respective holding tables R and 3. At this time, the mask stop electromagnet 18 is set to 0N, and the electromagnet of the electromagnet support 17 is set to 0FF. Further, the air circuit 25 blows out compressed air from the coarse movement air pipe 26 to maintain non-contact with the coarse movement interval 23 of several μm, while supplying compressed air to the fine movement air pipe 27 or pulling a vacuum or ζ. As a result, the mask stopping electromagnet 18 and the mask holding table 7 are fixed in contact with each other.

In this state, the relative positioning error between the mask 1 and the wafer 2 is detected from above using a microscope (not shown), and the
The motor 5, which is a coarse movement mechanism, is operated to move the wafer 3 and align the relative position to within a few μm. next,
The master stop electromagnet 18 is set to 0FF, and the electromagnet of the electromagnet support 17 is set to ON.

Furthermore, the air circuit stops or evacuates the compressed air to the coarse movement air pipe 26, so that the mask holding table 7 can be fixed in contact with the electromagnet of the electromagnet support 17, while compressed air is supplied from the fine movement air pipe 27. By blowing out air,
A non-contact state is maintained with a fine movement interval 23 of several microns. In this state, mask 1 and wafer are examined again using a microscope (not shown) from above.
The relative position error with respect to wafer 2 is detected, and the fine movement of wafer 3 is corrected by the above-mentioned close positioning mechanism by the amount of the error, and the wafer 3 is adjusted to 0.2μ.
Perform the following precise positioning. Therefore, by providing a means to maintain a non-contact state by blowing out compressed air or by vacuuming as described above, looseness and deflection when the coarse movement mechanism is moved, as well as deflection and looseness of the entire mechanism, can be reduced. Since the distance can be forcibly maintained regardless of the
The vertical movement of the mask holding table 7 is small, and the horizontal positional deviation error accompanying this can be reduced to a negligible order.

In Figure 5, for the sake of explanation, both the coarse movement mechanism and the fine movement mechanism are shown.
Although only one axis direction is shown, in reality, three directions (X, Y, θ) are shown.
It consists of the axial direction.

FIG. 6 shows another embodiment of the present invention, and the difference from FIG. 5 is that a magnet is used instead of air in the non-contact mechanism. First, for rough alignment, the mask stop electromagnet 18 and the magnet 28 are attracted to each other, and a voltage is applied to the electromagnet of the electromagnet support 17 so as to repel the magnet 28.
Make it contactless. In this state, the coarse movement table 7 is moved. Next, a voltage is applied to the mask stop electromagnet 18 so as to repel the magnet 28 to maintain non-contact, and the electromagnet of the electromagnet support 17 and the magnet 28 are attracted to each other.

In this state, the precision movement mechanism is activated. This method also allows non-contact to be maintained by adjusting the magnetic force appropriately.

Furthermore, by constantly measuring the distance between the magnet and electromagnet using a method such as an air micrometer, and providing feedback to the current control circuit, the distance can be maintained very precisely and even smaller. This feedback concept also applies to air non-contact mechanisms.

As explained above, according to the present invention, after coarse position alignment,
It is possible to reduce the vertical movement of the mask holding table during precise positioning to a width of a human width, thereby greatly reducing the horizontal positional deviation caused by the vertical movement, thereby reducing the stroke during dense positioning. This has the effect of enabling highly accurate positioning.

[Brief explanation of the drawing]

Figure 1 is a side view showing an example of a conventional precision positioning device;
Fig. 2 is a side view showing an example of a conventional precision positioning device equipped with a precision positioning mechanism different from the precision positioning mechanism shown in Fig. 1, and Fig. 3 is a drawback of Figs. 1 and 2. FIG. 4 is a side view showing an example of a conventional precision positioning device with a modified precision positioning device, and FIG. , FIG. 5 is a side view showing one embodiment of the precision positioning device according to the present invention, and FIG. 6 is a side view showing another embodiment of the precision positioning device different from FIG. 5.
...Masuku 2...Wafer, 4...
...Slide part, 5...Feed screw mechanism, 6...
...Motor, 7...Mask holding table, 9
...Base, 10...Parallel leaf spring, 13...
... Differential displacement meter, 15 ... Fine movement table, 1
6...Coarse movement table, 17...Electromagnet support, 18...Mask stop electromagnet, 19...
... Drive spring, 20 ... Elastic strut, 21.
... Drive spring compression rock structure, 22 ... Motor, 25 ... Air supply system, 26 ... Air pipe for coarse movement, 27 ... Air tube for fine movement.

Claims (1)

[Claims] 1. Arranging a first object and a second object whose positions are aligned,
A holding table on which the first object is placed is provided, a fine movement table on which the second object is placed is supported by a coarse movement table, and a displacement signal from a displacement detection means for detecting displacement of the fine movement table is returned. The coarse movement table is slidably supported on a base by a slide member, and the coarse movement table is slidably supported on a base by a slide member, and the coarse movement table is configured to be slidably supported by a slide member to operate the fine movement drive source to slightly displace the fine movement table. Therefore, the coarse movement table is configured to be coarsely displaced, and a first fixing means for fixing the holding table during coarse position alignment is attached to the base, and a second fixing means for fixing the holding table during fine position alignment. is attached to the coarse movement table, and when the first fixing means is actuated, the second fixing means applies a repulsive force to the holding table, and when the second fixing means is actuated, the first fixing means is attached to the coarse movement table.
A precision position alignment device characterized in that it is configured to apply a repulsive force to the holding table from the fixing means. 2. A patent characterized in that the means for applying the repulsive force is formed by pneumatic pressure or magnetic force, and the holding table and the first fixing means or the second fixing means are held in a non-contact manner. A precise position alignment device according to claim 1.